In a message dated 12/6/2006 12:23:36 PM Central Standard Time,
dkspence@telus.net writes:
> I'm collecting the bits to convert my 4A to TR6 braking system. I
> want the additional safety of a dual circuit system. What parts do I
> need to gather from the TR6?
>
> Any major problems in doing this?
I am also doing this to my 4A. Here's how I did it:
1- My driver side bulkhead was rusty at the bottom so I purchased a repair
panel for a TR250 from TRF that already has the holes for the brake servo
and clutch/pedal assembly. You will either need this bulkhead panel or
accurately cut yours.
2- The TR250-TR6 pedals mount on the front of this panel unlike the TR4 that
mounts on the top. You wil also need a TR6 pedal assembly and MC bracket.
The pedal/mc assembly on the 4 must be removed and is not reused.
3- Next is a TR6 servo/MC. Best price for the MC new was from Kai at
Wishbone Classics. I sourced my servo on ebay but was lucky to get a decent
one. You also need the aluminum spacer between the bulkhead and servo.
You should be able to reuse your TR4 clutch cylinder.
I chose to use a PDWA for plumbing convenience and plugged the switch tap
since I didn't have a switch. I plumbed from the front output circuit of the
PDWA to a 3-way connector for the two TR4A front lines. I then made up a
line to go from the PDWA rear circuit to a Wilwood manual proportioning
valve, from the proportioning valve to the existing 4-way connector location
which I replaced with a 3-way connector (where the original MC used to
connect to the front and rear.) The 3-way has 1) input from the
proportioning valve output, 2) line to the rear brakes, and 3)a bleed nipple
for bleeding the front of the circuit easier (and plugs the hole nicely!)
At the rear the TR4 uses just one bleed screw on the pass wheel cylinder for
bleeding. I added a 3-way mounted on the axle tube . This allows me to spilt
the rear to left and right cylinders and be able to bleed each rear wheel
cylinder independently. If you do this, make sure that you use flexible line
from the hard line from the front to the 3-way. Just make sure the the hard
line isn't part of the suspension, it needs a flexible connection.
Also, my 4A has Toyota 4-pot brakes so I changed the rear wheel cylinders to
.75" instead of .70" and will use the proportionvalve to dial in rear.
You will also need to fab a plate to cover the existing MC bracket holes.
Hope this helps.
PeterK
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